Micromachined devices with apertures

• US 6,925,877 B2
• Filed: 04/01/2003
• Issued: 08/09/2005
• Est. Priority Date: 09/02/1997
• Status: Expired due to Term

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Geen, John A., Carow, Donald W.
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US10/404,868
• Publication Number:
  US 20030200806A1
• Time in Patent Office: 861 Days
• Field of Search: 735/040.4, 735/041.2, 735/041.3, 735/041.4, 735/041.5, 735/041.6, 735/143.2, 735/143.6, 361/280, 361/283.1, 361/283.3, 310/309, 310/40.NM
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis

Abstract

A micromachined device has a body suspended over a substrate and movable in a plane relative to the substrate. The body has a perimeter portion, a first cross-piece portion extending from one part of the perimeter portion to another part of the perimeter portion to define at least first and second apertures, a first plurality of fingers extending along parallel axes from the perimeter portion into the first aperture, and a second plurality of fingers extending along parallel axes from the perimeter portion into the second aperture.

Claims

1. A micromachined device comprising:

a substrate;

a body suspended over the substrate in a plane parallel to the substrate and movable in the plane relative to the substrate, the body having;

a perimeter portion,

a first cross-piece extending from one part of the perimeter portion to another part of the perimeter portion and a second cross-piece extending from and perpendicular to the first cross-piece, the first and second cross-pieces at least partly defining at least first, second, and third apertures in the body in the plane,

a first plurality of fingers extending in a first direction in parallel in the plane and into the first aperture, and

a second plurality of fingers extending in parallel in the plane and into the second aperture;

the first and second apertures being aligned along a second direction that is perpendicular to the first direction.

2. The device of claim 1, wherein the perimeter portion is generally rectangular, and the first cross-piece forms two generally rectangular parts.

3. The device of claim 1, further comprising stationary fingers anchored to the substrate and interdigitating with the first plurality of fingers.

4. The device of claim 3, further comprising a dither drive coupled to the stationary fingers for providing a signal to cause the body to dither along a dither axis that is parallel to the first direction.

5. The device of claim 1, wherein the apertures are contoured to be only slightly larger than the size needed to provide the fingers and the stationary fingers.

6. The device of claim 1, further comprising stationary fingers anchored to the substrate and interdigitating with the first plurality of fingers to form capacitive sensing cells.

7. The device of claim 6, further comprising sensing circuitry for sensing movement of the first and second pluralities of fingers relative to the stationary fingers.

8. The device of claim 1, wherein the first plurality of fingers interdigitates with at least one stationary finger that is part of a dither driver mechanism used to drive the body in an oscillating manner along a dither axis, and wherein the second plurality of fingers interdigitate with at least one stationary finger for sensing the dithering motion of the body along the dither axis, each aperture having fingers that are used only for driving or sensing.

9. The device of claim 1, wherein the body includes n cross-pieces parallel to the first cross-piece to at least partly define at least n+2 apertures.

10. The device of claim 9, wherein each of the n+1 apertures has inwardly extending movable fingers, and within each aperture are stationary fingers that are not movable relative to the substrate and that interdigitate with the movable fingers, the stationary fingers being part of a dither drive mechanism to cause the body to dither along a dither axis.

11. The device of claim 1, wherein there are at least two apertures with fingers used to sense a dithering motion of the body.

12. The device of claim 1, wherein there are at least four apertures with fingers used to sense a dithering motion of the body, the four apertures being spaced near corners of the body.

13. A micromachined device comprising:

a substrate;

a body suspended over the substrate in a plane parallel to the substrate and movable in the plane relative to the substrate, the body having;

a perimeter portion,

a first cross-piece extending from one part of the perimeter portion to another part of the perimeter portion to at least partly define at least first and second apertures in the body in the plane,

a first plurality of fingers extending in parallel in the plane and into the first aperture, and

a second plurality of fingers extending in parallel in the plane and into the second aperture;

at least one connecting structure extending from the perimeter portion to the first cross piece and perpendicular to the cross-piece to further define at least a third aperture.

14. The device of claim 13, wherein the body is dithered in a first direction, the first plurality of fingers being part of a dither drive mechanism used to dither the body, the third aperture including a third plurality of fingers extending therein and used for sensing the dithering motion.

15. The device of claim 13, further comprising stationary fingers that are not movable relative to the substrate for interdigitating with each of the sets of fingers that extend into openings.

16. The device of claim 15, further comprising a dither drive mechanism coupled to at least some of the stationary fingers for providing a signal to cause the body to dither along a dither axis.

17. The device of claim 15, further comprising sensing circuitry for sensing movement of the fingers relative to the stationary fingers.

18. The device of claim 15, wherein the apertures are contoured to be only slightly larger than the size needed to provide the fingers and the stationary fingers.

19. The device of claim 13, wherein at least one aperture has inwardly extending fingers that are part of a dither drive mechanism used for driving the body in an oscillating manner along a dither axis, and at least one other aperture has inwardly extending fingers that are used for sensing the dithering motion of the body along the dithering axis.

20. The device of claim 19, wherein each aperture has only fingers that are used either for driving or sensing, but not both driving and sensing.